A PRE LIMINARY REPORT ON CLAYS OF FLORIDA 161


 Physical Properties of State Hospital Red Sandy Clay (Lab. No. 0-37).
 Plasticity, judged by feel............ Fair.
 W ater of plasticity................. 21.40%
 Pore water ........................ 0.10%
 Shrinkage water ................... 21.30%
 Linear air shrinkage................ 6.40%
 Volume air shrinkage............... 17.90%
 Modulus of rupture, average........ 84.5 pounds per square inch.
 Slaking test ....................... 36 hours.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 0.6 22.37 36.70 Brick red.
 1050 0.6 18.40 36.50
 1150 1.4 17.45 36.50

 A surface clay. exposed on the A. J. Key Plantation, about three miles southeast of Quincy on the Seaboard Air Line Railway, contained numerous lirnonitic concretions. The plasticity and drying qualities are good, but the transverse strength is very low. This clay is of no practical value for the manufacture of burned products. Its physical properties are:
 Physical Properties of Key Plantation Clay (Lab. No. o-41).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity................. 24.75%
 Pore water ........................ 0.27%
 Shrinkage water ................... 24.48%
 Linear air shrinkage................ 5.70%
 Volume air shrinkage............... 15.75%
 Modulus of rupture, average........ 92.5 pounds per square inch.
 Slaking test ....................... 24 hours.
 Overfires at cone 5.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 0.3 26.60 45.80 Brick red.
 1050 0.8 24.48 43.10 Brick red.
 1150 2.3 23.55 43.60 Brick red.
 1190 3.3 16.70 37.10 Brick red.

 By far the best clays in the county for burned products are the flood-plain clays along the Apalachicola and Ocklocknee rivers. One such deposit is located on the State Hospital Farm, about one mile northwest of Chattahoochee, in a field joining the Apalachicola River and the Georgia-Florida boundary. The thickness of this deposit is not definitely known, but it is more than five or six feet. It is known to underlie an area of sixty or eighty acres in Georgia and Florida.